Metallized film capacitors generally include capacitors using metal foil for electrodes and capacitors using evaporated metals on dielectric films for electrodes. Among these capacitors, a metallized film capacitor using a metal-deposited electrode of an evaporated metal has a smaller volume occupied by the electrode than that of a metallized film capacitor using metal foil, and can have a small size and weight. The metal-deposited electrode has high reliability to breakdown due to a self-recovery property, which is unique to the metal-deposited electrode. When a short circuit occurs in an electrical insulation defect portion, the metal-deposited electrode is evaporated and scattered around the defect portion by energy of the short circuit and is insulated so that function of the capacitor recovers. In view of these properties, metal-deposited electrodes have been widely used to date.
FIG. 10 is a top view of metallized film 100 for use in a metallized film capacitor disclosed in PTL 1.
As illustrated in FIG. 10, metallized film 100 includes dielectric film 101 and metal-deposited electrode 102 formed by vapor depositing a metal on a surface of dielectric film 101. Metal-deposited electrode 102 is divided into non-segmented electrode part 104 and segmented electrode part 106 by slit 103 extending in a longitudinal direction of dielectric film 101 (a lateral direction in FIG. 10). The inside of segmented electrode part 106 is divided into plural electrode segments 105.
Non-segmented electrode part 104 is electrically connected to segmented electrode part 106 via fuses 107 disposed in slit 103. Electrode segments 105 adjacent to each other are electrically connected to each other via fuse 108.
When an electrical insulation defect portion is produced in one of electrode segments 105 in a conventional metallized film capacitor using metallized film 100, fuse 107 or 108 is blown by a current flowing into electrode segment 105. Consequently, electrode segment 105 including the electrical insulation defect portion is electrically isolated, hence avoiding occurrence of a defect, such as a short circuit, of the metallized film capacitor.
The conventional metallized film capacitor thus has a self-protection function due to fuses 107 and 108 provided in metallized film 100.
PTL 2 discloses a metallized film capacitor using an aluminum-zinc layer.